Coupler for television signal distributing systems



Nov 17, 1959 c. SEIFERT 2,913,579

COUPLER FOR TELEVISION SIGNAL DISTRIBUTING SYSTEMS Filed Dec. 25, 1957 zshets-sheet 1 mamas aws/Q7;

INVENTOR.

COUPLER FOR TELEVISION SIGNAL DISTRIBUTING SYSTEMS Filed Dec. 23, 1957 C. SEIFERT Nov. 17, 1959 2 Sheets-Sheet 2 121 111 9; 149 I v CHM/.55 5M 10. IINVENTIORT BY Ms flrrmug/s v United States Patent Qflice 1 2 t Fig 3 is'a sectional view taken along theline- 3' 3 of Fig. 2; l 4 is a perspective view of an alternative embodi 2,913,679 ment of the invention;

I A COUPLER FOR TELEVISION SIGNAL r 5 lining-55 15f ziznigerlitlarged sectional v1ew talren along the DISTRIBUTING 1 Fig. 6 is a sectionalview taken along the line 6---6 Charles Seifert, Los'Angeles, Calif; v of Fi '5; e l v Y Y L i i I e Fig.7 is anexploded view of the coupler of Fig.4; f Aprl t December 3 1957 fl 'm l Fig; 8is a perspective view of another alternativeem 10 Claims. (Cl. 333-24 bodiment :of the invention; 1 Fig. 9 is an enlarged partial sectional view of the em bodiment of Figure. 8; and V I Fig. 10 is a sectional view taken along the line 10-510.; This invention relates to a coupler for'transferring f F i 9 I a ,v H 1. I energy in theradio frequency range between ,tw0 pPe u In a first transmission lin e 15 consisting ,Qf: or spac ed wiretransmission lines. "Theinventloil Isl-p 81- conducto rs l d, .17 is supported [by a plurality of ,intiblilarly adapted to coupling mm? 1 f e fls n ma i taten. $5- 1Y;Q2 in shswn. audit-a r:- receivers to a single antenna without interference' or'crqss' minated in aload resistor19, the magnitude of the reslsr, coupling between the individual'receive'rs' tor preferably being equal to the characteristic impedance -Thisapplication is a continuation-in-part of my copeiid; of the line.v A second transmission line 20 comprising ing application entitled Coupler for Television Distribut-f conductors :21, 22, is coupled to the first transmissi ing Systems, Serial No. 470,376, filed November 22, line 15 a coupler 23. The second transmission line 3 v i s-.'supported an insulating spacer 24 and is terminated 'It is an object of the invention to provide a transniis: 25 in a load "resistor 25 which is also preferably equalto sion line coupler which may be used with a plural ty of 1 tl lgpcharacter isti c impedance ofthe line. A third tra i il eo lersto feed a plurality ofloads, from asingle miss on line 26 comprising conductors 27, 28 supported transmission line without introducingadditional intera solid dielectric 29;, is coupled to the second line 20 ference betweenthe' loads while having very small line by a coupler 30, l a losses. A further object ofthe invention is to jprovi de 30 The left end of the line 15 may be-pbnu ted .3 alcbuplerwhic hban be attached to and remoyedhflrom antenna or other source of radio frequency energy and a-ztransrnission line at will andflwhich can be movejd to the-right end of line 26 maybe connected to a,t eley ision position along the line as. desired. receiver or'otherload. Additional lines similar to the It is a further obje of tion to'provide a lines Zlland: 26 may be coupled to the line 15 and addicoupler which does not require. direct contact between tlonal llnes may be coupled to the line 21) in the manner, the conductors of the two transmission; lines, eliminating shown herein. lWh en desired, the-line 20 may be jtt d. all soldering, splicing and cutting, so that t heffcouplei", and the line 26 coupled to the line 15 or theline' 26 may; maybe removed; leaving no evidence of it'slpresencet on. e pulltted and the television receiver or other load sub1- the-transmission line. Another object isito proyid'e such 40 stltutedfor the load] resistor 25. 5 1;; a a transmission line;c oupler which may-bereadily applied: lhe couplers 23 and 30 are identical and aret' ho to the linei by merely positioning the couplerastride'thel 1* 1n detall in Figs. 2 and 3 A hollow housing 33 of Linconductors of the line whereby radio rrequencyedfipnng; sulatlng material such as molded plastic or the" like is is effected without the use of clamps or tools. medfwith upper and lower halfsections 34, 35.x The Itwis afurtlier object of he invention to provide a"; half scctlons are joined togetherby suitable means such transmission line coupler embodying a pairfof wading, asby eementing, providing flat top and bottomwalls 36,. title tubes or cylinders, having. slots therein and adapted lq' l, flatsidewalls 38,39, and roundedend walls 40, 41'.- to be individually positioned around each conductor for the housing 33. M of a linewhereby. the tubes may be readily disposed and Spaced upstanding or inwardly projecting pairs. of, securelyheld in coaxial spaced relation to the conductors. parallel or nearly parallel walls 44, 45 extend laterally Another object of the invention is to provide a coupler." Qflhe lower sectio n and form a pair of transverse spaced suitable for television distributing systems embodyin ga parallel Open ended slots 46, 47 in the lower section. longitudinally slotted conductive tube for positioning upper-ends of the walls 44, 45 are joined together. around the-conductors of a transmission line in. which y an arcuate endwall 48 which extends mediate thefltop means are provided for supporting the'tube coaxially iof and bottom walls 36, 37 so as to lie on a plane at or the line out of physical contact therewith and iiilspaced. near the horizontal center of the housing. relation thereto and whereby thetcoupler may be applied Cyli ders or tubes 5 52 ofan electrical conducting to the line by merely. disposing its supporting means material such as aluminum, are split longitudinallyand astride'the liu in ffictiOIlal gfi ent therewith, positioned astride the upstanding pairs of walls 44, 45 in" I-he invention also comprises novel details of con gripping engagement therewith. The cylinders are prefstruction and novel comblnatlons and arrangements of erably, ofiilengths coextensive with lengths of the Walls P w i r fully m thepourse of 44; '45 and accordingly have their ends abutting the inner fQ110W1l1g Escuptlon The flrawmgs merely w. faces' of the side walls 38, 39.' The diameters-of the" the desglpuqn merqly descnPes preferred mi d q cylinders preferably are such that the cylinders will Invention which are gwen by Way 9 lustmuon snugly fit between the walls 36, 37, the cylinders thus be orlelxal iplgiawings ing seated in the housing 33 and securely held. Fi 1 is a ers ective view showing the coupler. oftthe in m e re1at1ve t9 the housmgn f inverftion as i ised in coupling a plurality of transmission The walls 445 i fin each q lfl 1, lines; 1 47 are. preferably positioned so that the arcuate wall 48 Patented Nov. 17, 1959 will be concentric with the axis of the cylinder po sitioned i Fig. 2 is enlarged sectional view taken along the p H v 1 thereabout so that when a conductor is pes t gped n ine 2.- o F 1;

cylinder' by'suitable means such as :by" soldering, a tang 56 at the other end positioned in an'opening inthe'housing, and an intermediate plate portion 57 'disposed'against the exterior of the housing, the plateportionihaving. a threadedopening therein for receiving a screw In use the coupler is positioned astride a transmission line with a conductor in each of the slots 46, 47, ,as 'seen in Figs. 2 and 3, thus positioning the conductors substantially at the centers of the corresponding cylinders. The slots 46, 47 are formed'of a widthsuch that the conductors therein will be firmly gripped by thewalls 44, 45 and frictionally engaged therewith so that the housing 33: will be held securely in place on the pair of conductors. without the use of extraneous fastenings. Thecoupler is removed from the line merely by applying sufiicient manual force to overcome the frictional grip. of the side walls of the conductors.

' After the coupler has been placed on the transmission line, the coupler may be moved back and forth along the line until a maximum or optimum signal is achieved. Additional couplers may be placed atintervals along the line, witheach being adjusted for an optimum or maximum signal. 7

An alternative embodiment of the invention is shown in Figs. 4, 5, 6, and 7, wherein the two conducting tubes or cylinders are carried in separate housings so that the coupler may be used with lines having 'various. spacings between conductors. Referring to Fig. 4, two couplers 61 are positioned on conductors 62,- 63 of a transmission line 64, the conductors being supported by an insulating spacer 65. One of the couplers 61 is shown in detail in FigsfiS, 6, and 7. A housing 66 of an insulating material such as a molded plastic is formed of two shells '67, 68

which are'identical with the exception of, bosses 69 ion the shell 67 which engage openings 70 in the shell 68 for aligning the shells when they are joined to form'the' ally gripping the conductor and with the conductor sub-' stantially coaxial with the longitudinal axis of the chamber 73 when the conductor engages the top wall 76.

A tube 80 of electrical conducting material andpre ferably having the same form'as the chamber 73 is positionedin the chamber 73, the tube having a slot 81 therein forralignment with the slot 77 of the housing. In the particular embodiment illustrated herein, the tube-80. is formed from a piece of flat material and is provided with integral, apertured tabs or terminals 82, 83 at the respectiye edges of the slot. Openings 78, 79 are provided in the walls 74, 75, respectively, adjacent the outer shell for passage of the tabs 82, 83. a

The shells 67, 68 are butted together with the tube. 80 positioned therein, substantially as shown in Fig. 6, and the two shells are fixed together by suitable means such as by cementing. The coupler may then be placed on a transmission line with a conductor in the slot. Then a to the tube (Fig. 4). Another coupler is similarlyplaced on the other conductor of the transmission line and the twounits may be moved along the line to function infthe' same manner as-the single unit of .the embodiment of Figs. 1, 2, and 3.

Another alternative embodiment of the invention which is particularly suited for use with transmission lines in which the conductors are spaced by a continuous solid dielectric is shown in Figs. 8, 9, and 10. Of course, the structure of this embodiment is not limited in use to a line with a solid dielectric but may also be used with lines of the type shown in Fig. 4. In Fig. 8, a coupler 90 is positioned about a-transmission line 91, the latter comprising conductors 92, 93 carried in a solid dielectric 94.

The coupler 90 is. formed of two housing units 95, 96 having corresponding longitudinal slots 97, 98, respectively therein, thetwo units being positionable on oppositesidesof the transmission line for joiningto each other with the slots aligned toenclose the transmission line therein.

The two housing units 95, 96 are substantially identical with the exception of the particular means for fastening them together. The unit 96 includes an outer shell 101 having sides 102, 103, ends 104, 105, and a top 106, the slot 98 extending through the ends. A'U-shapedplate or slotted tube 107 of electrical conducting material is positioned within the shell 101 and a U-shaped inner shell 108 of insulating material is positioned inside the plate 107, the open center of the U serving to define the sl ot'98. The inner shell 108 includes longitudinal ribs 101 on opposite sides of the unit transverse to the slot 98.

. A hollow boss 113 projects outward from the top 106 of the outer shell and a threaded metal plug 114 is positioned within the boss 113, the plug being fixed to the plate 107 by suitable means such as by a rivet 115. A

screw 116 is threaded'into the plug '114serving as a ter'-' minal for connecting a conductor 117 to the plate 107;

' Thehousing ur1it'95v is similar to the housing unit 96 except for the ribs of .the inner shell, the ribs being provided with curved'end sections 121, 122 providing grooves for slidingly receiving the ribs 111, 112, respectively. I

The end 104 of the outer shell of a housing unit preferably extends slightly beyond the center line of the slo't,-jbeing terminated in a concave section 123 (Fig. 9) while the end 105 does not extend to the center line of the slot and is terminated in a convex section 124. The coupler is mounted on a transmission line by placing the twohousingunits on opposite sides of the line with the unitsdisplaced' from each other along the longitudinal axis .of the line with the unit to the right as viewed in Fig. 9. Then the units are moved toward each other along the line to slidingly engage the ribs of one unit in the corresponding grooves of the other unit to bring the units to. the position shown in Fig. 9 with the trans mission line frictionally gripped therebetween. The

1 matingconcave and convex sections of the ends ofthe outer shells engage each other to provide a snap action forholding the two units together.

Thus this embodiment of the coupler of the invention may also be placed on and removed from a transmission line as desired and may be moved to any position along' the .line'without requiring any physical connections to the line such as splicing, taping, cutting and the like.

The most obvious method of coupling one open two wire transmission line to another or a balanced twin feeder line to an open two-wire transmission line, would be to solder, tape, or otherwise establish direct electricalconnection between the appropriate conductors of the two lines. Such a method of direct electrical connection would cause impedance mismatch, with a resultant large standing wave ratio, voltage reflections, deterioration of parallelism between the appropriate conductors of two 1 open two-wire lines. Such an arrangement, however, while feasible in certain applications, has the inherent disadvantage that, in order --toobtain sufiicie'ntly good coupling, the length of parallelism required may approach a quarter wave length of the radio frequencies being transmitted. This, inturn, hasa deleterious effect upon the transmission of the radio frequency signals, and upon their quality. Thus, essentially, this method of transfer of energy is limited either as to the amount of coupling possible, or as to the bandwidth possible. Furthermore, the placing of the conductors of one line in close juxtaposition to the conductors of another, has an effect upon the characteristic impedance ofthe latter, and this elfect is increased with length of parallelism. Thus, again mismatch is caused, with its attendant undesirable effects upon the radio frequency signals being transmitted. The present invention achieves closer coupling than is possible with parallelism, so that the limitations, particularly. as to bandwidth, are considerably less, so that the invention is, in practice, able to be used satisfactorily over the entire VHF television frequency spectrum. An important feature of the coupler of the invention is its small size. For example, the particular embodiments shown herein are being used with present day television systems including 450 ohm and 300- ohm transmission lines with the conducting sleeve or tube being in the order of one to one and one half inches in length and one quarter to one half inch in width;

Although exemplary embodiments of the invention have been disclosed and discussed, it will be understood that other applications of the invention are possible and that the embodiments disclosed may be subjected to various changes, modifications and substitutions without necessarily departing from the spiritof the invention.

pairs of radio frequency transmissionlines comprising:

an insulating housing having a top wall, a bottomwall, side walls and end walls, said bottom wall being formed; with spaced pairs of upstanding spaced walls leading 1 transversely thereof and bordering line receiving slots which open through said bottom and side walls; interior top walls connecting't'he upper ends of each of said pairs of upstanding walls; a hollow, axially split, open ended, conductive cylinder positioned astride each of said pairs of upstanding walls in engagement with the lower portions thereof with said interior top walls concentric with said cylinders; and a conductor leading from each .of said cylinders.

6. In a coupler for a two wire transmission line, the combination of: first and second members of insulating material having longitudinal slots therein and means for joining said members together with said slots aligned to provide a substantially rectangular passage through said joined members for receiving said two-wire transmission line with one wire in each slot; a first axially slotted tube of electrical conducting material carried on said first member and positioned about the slot therein; a second axially slotted tube of electrical conducting material carried on said second member andpositioned about the slot therein; and means for connecting conductors to each of said tubes.

. joining the open sides of the units to define a passage I claim as my invention: v

1. In a coupler for an open wire transmission line, the combination of: a pair of metallic, axially slotted tubes; housing means for frictionally engaging the Wires of the line, said housing means including means for supporting said tubes thereon for positioning a tube coaxial with a wire when said housing means is frictionally engaged with the wire, with said housing means spa-cihg'said tube from the wire; and means for connecting an electrical conductor to each of said tubes.

2. In a coupler for television distributing systems embodying a pair of radio frequency conductors, the combination of: an insulating housing formed with a pair of spaced transverse slots on its underside for reception of conductors; a pair of upstanding side Walls carried within said housing and bordering opposite sides of each of said slots; a conductive, axially split cylinder positioned astride each pair of said walls within said housing; an end wall connecting each pair of said side walls and adapted to seat on a conductor leading therebeneath, said walls being arranged to position the conductor in the slot bordered thereby coaxially with the associated cylinder in spaced relation thereto; and a conductor leading from each of said cylinders.

3. A device for transmitting radio frequency between pairs of radio frequency transmission lines comprising: a pair of spaced, parallel, axially split conductive cylinders; an insulating housing carrying said cylinders having pairs of spaced upstanding walls i'nteriorly thereof astride of which said cylinders are mounted, each of the spaces between each pair ofwalls being adapted to receive one conductor of a transmission line; means for positioning lines in said spaces in coaxial spaced relation to said cylinders; conductors leading from said cylinders; and binding posts connected to said conductors.

4. The structure called for in claim 3 in which the pairs of spaced walls frictionally grip a line interposed therebetween.

5. A device for transmitting radio frequency between for said two transrm'ssion line wires therethrough with one wire in each unit, each of said units including an outer member of insulating material, a central member of conducting material, an inner member of insulating material positioned within said central members for spacing said central members from the transmission line, said inner members defining the inner faces of said channels, and means for connecting a conductor to said central the line and having opposed longitudinal ribs projecting outward therefrom; a first axially slotted metallic tube mounted in said first housing for positioning around the conductor in the slot; means for connecting a conductor to said first tube; a second housing of insulating material having a longitudinal slot therein for gripping the other conductor of the line and having opposed longitudinal grooves for longitudinal sliding engagement with said ribs of said first housing to join said housings about the transmission line; a second axially slotted metallic tube mounted in said second housing for positioning around the other conductor in the slot of said second housing; and means for connecting a lead to said second tube.

-. 9. A coupler for mounting on a transmission line having two conductors spaced by a solid dielectric, with the coupler slidable along the line to any desired location,

stantially rectangular passage for the transmission line with one conductor in each of said slots, the housing having means for joining said members together to grip the transmission line therebetween; an axially split metallic tube carried in each of said members with the tube encompassing the slot; and means for connecting a lead to each of said tubes to couple said lead to the transmission line.

10. In a device for coupling a first transmission line to a second transmission line, the combination of: a hollow housing section of nonconducting material having a circumscribing peripheral wall and end walls, a portion of said peripheral wall being of generally U-shape and extending into said housing to define an outwardly facing open channel; slots in said end walls in alignment with the ends of said channel whereby said housing may 8 7 transmission line; and conducting terminal meanseXtending-from said conducting element to the exterior of said housing.

References Cited in the file of this patent 'UNITED STATES PATENTS 1,838,987 Cooper Dee. 29, 1931' 

